Biofilms form when bacteria interact with a surface to form polymeric films (sometimes referred to as exopolysaccharide or extracellular polysaccharide (EPS) polymers) that coat the surface and provide a living colony for further bacterial proliferation. Bacteria lodged in biofilms are much more difficult to remove or kill than bacteria in a planktonic (suspended) state, and are resistant to many antibiotics and biocides.
When present on human tissues, bacteria and biofilms can cause chronic conditions from which many persons today suffer. Such conditions include rhinosinusitis, where biofilms are attached within the nasal passages and sinuses. Implants or surgical devices may also be enclosed or encased within biofilms, which may lessen the implant's or surgical device's effectiveness.